I've checked and this route is usually operated with a plane with crew rest bunks, hence 4J AND 4K being selectable. It's a whole other thread, but there have been cases where these have been selectable, then blocked/passengers turfed out nearer the time. I understand in your case that your plane was changed to CS and back again, which is slightly different. As others have said, there will be a lot of displaced people so hopefully it will work out.